To be honest, I find both of the sentences awkward for the following two reasons:

1. If a country has good infrastructure, it's usually not labelled as a developing country. "Developing" is a euphamism for "poor" or "relatively poor." So, if you replace "developing" with "poor/relatively poor" in your example sentence, you will see and feel its awkwardness and how paradoxical it is: "Good infrastructure is important to be/in order to be a poor country."

2. One of the functions of infinitive is to express purpose. (See "Purpose of Infinitive' ) You do something to/in order to get somewhere, achieve something, etc. I would find it strange that any country would want to aim at becoming a developing country.